11 Questions
What is the color obtained when Dragendorff’s Reagent is used to detect alkaloids?
Reddish-brown
Which reagent is commonly used for the detection of caffeine based on its yellow color obtained?
Hager’s Reagent
What color is typically obtained when mineral acids are used for the detection of alkaloids?
Yellow
What chemical composition is present in Marquis Reagent used for detecting amphetamines and opiates?
Formaldehyde and conc.Sulfuric acid
In the detection of colchicine, which chemical composition results in a bluish-violet to red color?
p-Methylaminobenzaldehyde and sulfuric acid
What color is obtained when Hager’s Reagent is used for the detection of alkaloids?
Yellow
Which reagent is used for the Murexide Test and results in a purple color?
Potassium chlorate + HCl + NH3
Which reagent, when used, results in a reddish-brown color in the presence of alkaloids?
Wagner’s Reagent
What color is typically obtained when Tannic acid is used for the detection of alkaloids?
Yellow
Which chemical composition is present in Dragendorff’s Reagent?
Potassium bismuth iodide solution
In the detection of morphine, what chemical composition results in a deep purplish red color?
Formaldehyde and conc. Sulfuric acid
Study Notes
Reagents Used in Detection of Alkaloids
- Mayer's Reagent: potassium mercuric iodide solution, produces a cream-colored reaction
- Wagner's Reagent: solution of iodine in potassium iodide, produces a reddish-brown reaction
- Dragendorff's Reagent: potassium bismuth iodide solution, produces a reddish-brown reaction
- Hager's Reagent: saturated solution of picric acid, produces a yellow reaction
- Picrolonic acid: picrolonic acid solution, produces a yellow reaction
- Tannic acid: produces a yellow crystalline precipitate
Reagents Used in Detection of Specific Alkaloids
- Murexide Test: potassium chlorate, HCl, and NH3, produces a purple reaction (caffeine)
- Mineral acids: phosphotungstic acid and phosphomolybdic acid, produce a yellow reaction
- Acidic p-methyl aminobenzaldehyde: p-methylaminobenzaldehyde and sulfuric acid, produces a bluish-violet to red reaction (colchicine)
- Nitric acid: dilute nitric acid, produces an orange-red reaction (indole)
- Marquis Reagent: formaldehyde and concentrated sulfuric acid, produces:
- Purple to black reaction (ecstasy)
- Orange to brown reaction (amphetamine)
- Deep purplish-red reaction (morphine)
This quiz covers various reagents used in the detection of alkaloids, their chemical composition, and the color obtained as a result. Examples include Mayer's Reagent, Wagner's Reagent, Dragendorff's Reagent, Hager's Reagent, and Picrolonic acid.
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